1.1 Technical Field
The present invention relates to a method of wrapping containers, and articles obtained by such a method. More particularly, the present invention relates to a method for shrink-wrapping two portions of a container simultaneously by using a wrapping material having a perforation thereon.
1.2 Description of Related Art
Heat-shrinkable films have been widely used to wrap containers. When a heat-shrinkable film is applied onto the body portion of a container, it usually serves several purposes. First, the heat-shrinkable film can be a protective means for the container preventing potential damage caused in handling the container. Second, it can be used as a label having a trademark or specification of the product printed thereon. When a film is formed on the neck portion of the container, it can also serve as a sealing means. This is needed especially when the container's contents are volatile or oxygen-sensitive, such as food and certain pharmaceutical products.
Conventional processes for forming a body wrap or a neck wrap generally involve forming the heat-shrinkable film into a sleeve slightly larger in diameter than the dimension of the portion of the container to be wrapped, placing the sleeve over the container, and heating the sleeve to shrink it onto the container. Typical wrapping processes are disclosed in U.S. Pat. Nos. 4,013,496, 4,016,706, 4,983,238, and 5,240,529.
In such typical processes, only one of the body portion and the neck portion of the container are wrapped. If both the body wrap and the neck wrap are to be formed on the same container, one possible approach is to form the two wraps separately in a sequential manner. However, there is a problem that the earlier-formed wrap may be overheated as it would have to be exposed to the heat applied to shrink the wrap to be formed later. Efficiency of the procedures and ease of operation would also be an issue of concern. None of the above-mentioned patents recognized these problems inasmuch as they relate either to the formation of a body wrap or the formation of a neck wrap. Therefore, it would be highly desirable if the two wraps can be formed on the container simultaneously in the same procedure.